


Hero Across Dimensions

by easternCriminal



Category: Sonic the Hedgehog - All Media Types, 僕のヒーローアカデミア | Boku no Hero Academia | My Hero Academia
Genre: Crossover, Gen, humanization, kind of
Language: English
Status: In-Progress
Published: 2019-08-25
Updated: 2019-08-26
Packaged: 2020-09-26 02:15:17
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 2,598
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20382013
Author URL: https://archiveofourown.org/users/easternCriminal/pseuds/easternCriminal
Summary: The teachers at UA just want to keep them safe, and Knuckles, Tails, and Sonic just want to find a way home.





	1. Chapter 1

**Author's Note:**

> this was just... super impulsive. I don't really know why I wrote, but I guess here it is.

“Are you sure it’s safe to investigate?” Hizashi asked, warily looking into the crater. Toshinori had gone to make sure that the students, particularly the ever curious and getting into trouble class 1-A, stayed in their dorms. Whatever had caused the crater hadn’t fallen from the sky - no one had seen and the cameras showed no trace of a stray meteor of any sort. It simply had come into being with an all too violent blast that shook the earth and left classes in a frenzy. 

“Nemuri, come with me.” Aizawa flicked his hand over at the other teacher and then began slowly making his way down the side of the crater, Midnight following close behind. “If whatever it is turns out to be hostile I can stop their quirk while you can put them to sleep - they should hardly notice with all the debris in the air.” 

“Good thinking.” Nemuri nodded and took off her jacket, tying it around her waist. The tank top she had on under it left plenty of her skin open to use her quirk quickly and effectively.

The pair went slowly, evenly. Aizawa in particular was known for his stealth ability, and used it to its full capabilities. Caution rolled off of the two as they approached the bottom of the crater. Through the dust a clump of… something could just barely be made out. Nemuri tapped Aizawa on the shoulder and made a few quick hand signals before going around to the other side. Once she was in position the finished their approached, Midnight’s fists up and ready for a fight, Aizawa’s capture tape floating around him like a cobra ready to strike. 

The clump was not a bomb. Not a meteor. It was not even a single person. Instead, in a haphazard and painful looking pile was three unconscious people and-

“Oh God.” Nemuri said, raising a hand to her mouth. “They’re children.”

  
  


Technically, upon getting some help and carrying the kids to one of their school informaries, two of them were most likely teenagers. All three of them had obvious quirks, the extent of which was unknown. 

The smallest one, a child with fair skin and blonde hair, had two very obvious fox tails. Whether that was where the quirk ended was up for debate, although it did make several of the teachers think of the hero Kyubey, with their nine tails and power over flames. Another of the boys had tan skin and blue hair, which seemed to be made out of quills not unlike that of a porcupine, although they were only on his head, and with the sides of his hair shaved it couldn’t be that effective unless he could shoot them out in some form. Last of the kids from the crater was dark skinned, hair a violent shade of red. His hands each had two horn like things coming out of the knuckles and his fingers ended in deadly looking claws almost like a bear. 

Despite the explosion that had accompanied their arrival all three boys seemed to be in relatively good health, although all the tests they were able to do for now were as non-intrusive as they could manage. Going through quirk databases was tedious work to try and find their identities, especially since they didn’t know the full extent of them. 

“Who would do that to- to children.” Toshinori sat looking at the slumbering forms, Principle Nezu sitting next to him. “ _ Children _ .” He emphasized under his breath. Nezu reached over and patted Toshinori’s hand comfortingly 

“Do not worry my friend. We are doing out best to keep this under wraps - whoever it is that wishes harm to come to these children will not hear about them from us and will not find them here.” Toshinori nodded, but his eyes stayed focused on their still bodies. 

Sonic rose slowly out of unconsciousness. First he could feel his hands, cold and bare, and instinctively they curled in on themselves so unused to the feeling on air on them. Wherever he was it felt cold, much colder than the workshop in Mystic Ruins. There was an annoying beeping sound, it didn’t sound like any of Tails’ most recent project, and it’s persistence grated on his nerves.. His memory of the past little bit was still fuzzy, but his preservation instincts kicked into gear first and foremost. 

He opened his eyes. 

Between the white walls and the smell of chemicals, the a-little-too-itchy bed sheets Sonic’s mind helpfully supplied that he was in the hospital. How he’d gotten there was still a mystery and he sat himself up, surprised by how… incorrect he felt in his own body. He went to adjust the sheets and saw his hands, bare like he had suspected, but also so distinctly… human. 

It didn’t surprise him as much as it probably should have. After going through so many transformations in his life, from a werehog to Super Sonic, this kind of thing stopped having such a gut punch. Taking stock of his surroundings, one of those things that he had to learn after getting into so much trouble, he first noticed that he was not along. Over to his right was a human stranger - unconscious with bright red hair. He glanced over to his left and that was when surprise actually began to take hold. 

While Sonic himself may be used to having physical changes, he was not as used to it happening to those around him. And he was fairly sure that the person next to him was in fact his brother. The way his had flopped in front of his fact, the pair of tails that had snuck out from under the covers and were wrapped around one of his arms was a dead give away. And if that was Tails, then… Sonic turned back to his other side, and gave the stranger a more appraising look. The line between his eyebrows, his face in a frown… it had to be Knuckles. 

Maybe one of them could recall how they had gotten into this mess. One friend at a time though. 

“Hey, Tails, wake up.” He shook his brother lightly who let out a few moans and batted his hand away. 

“Five more minutes Sonic.” 

“Buddy now really isn’t the time for a nap.” 

“What is… it…” Tails’ voice died out as he caught an eye full of Sonic’s undoubtedly very different visage. “Is this another werehog scenario?” Tails let out a groan and his namesakes began to move irritably. “If we have to fight another world breaking demon-”

“Ain’t just me this time pal, might wanna take a look at yourself.” Tails slowly looked down at himself, letting out a yelp. 

“W-what? How?” 

“Trying to figure that out-” 

“It must have to do with the Chaos Emeralds.” Both of them jumped and Sonic turned around sharply to see Knuckles was sitting half on his bed, feet dangling off the side, inspecting his hands. “The Master Emerald is being oddly distant, but it’s still there.”

“How long have you been awake?” Sonic asked, spooked that it had taken him this long to notice. 

“Don’t worry, I just came to. For now it seems best that we get out of here and try to find the seven-” He was interrupted by a knock on the door, and the three immediately made eye contact with one another. Words went unsaid but loudly heard - you didn’t spend as much time working together as they did and not develop the ability to communicate quickly and without speaking. They were officially ont he defensive, and anyone unknown was a presumed enemy.

“It’s good to see you kids are awake…” 


	2. Chapter 2

“...can you tell us where you were before this?” Sonic fidgeted in his seat. They had been sat down on a couch in the small mouses office after they had gotten the okay from the nurse that they were all in good health. Sonic wasn’t entirely sure about that part - he’d have to get Knuckles check up on their Chaos levels. Their appearance alone said that everything was not okay. But now wasn’t the time for that. 

“I don’t think-” Knuckles started, and Sonic was prepared to have to cover up for whatever he said. Subtlety and lies has never been his strongest suit.

“Whaaa!” Tails suddenly let out an incredibly loud and shockingly believable cry, letting tears fall out of his eyes and plop onto his overalls. Instantly Sonic turned to him, putting his arms around him and making the best coddling sounds he could. “I- I can’t-” Tails continued to choke on the words. 

“I’m sorry sir.” Sonic said, glancing away from his brother. “It’s still a very sore subject for us, we’d rather not talk about it.” The small mouse shared a look with his companion, a tall and lanky skeleton looking dude, before letting out a sigh. 

“Very well, perhaps you can at least tell us where you’re from? We’d like to return the three of you safely home. Trust me when I say that we will not let you go unprotected. Several of our staff will go with you to ensure that you are guarded until the time comes that we have found whoever hurt you so.” On the outside Sonic tried to look thankful, but internally his mind was reeling a thousand miles a minute. So they weren’t just going to let them go then - faking an address wouldn’t be adequate in this scenario. 

“We don’t remember.” Knuckles stepped up to the plate this time. “All that’s left is… that place. And each other.” Knuckles looked down at his hands in a truly commendable act of remorse and sorrow. Sonic and Tails nodded along, and Tails threw in a few more wails and tears to add to the web of lies that they were weaving on the fly. 

“I’m so sorry.” Sonic glanced over and finally caught sight of the mouses nameplace. Principle Nezu. “I’m afraid that for the time being we’ll have to keep you here under our watch. We will do everything in our power to help you memories. We have some dorms on campus and I’m sure we can find room for you.” He looked at his companion again. “Toshinori, your dorms are some of the best reinforced…?” The skeleton man - Toshinori - gave an affirmative nod. 

“Of course. I’ll protect them with my life. We can make room.” Still gripping him with his arms, Tails tightened his hold. This wasn’t much better than faking an address for a family. It sounded like they were going to be stuck here for the time being. 

“Well the best start to finding your families is going to be the quirk registry.” Nezu said thoughtfully. “Why don’t we have you kids - if you’re able to - come down to one of our gyms and show us your abilities. Unless you can recall their registered titles?” Nezu asked hopefully. Well, Sonic definitely didn’t know like half of what Nezu was referring to, so he shook his head, the other two following his lead. “Will the little one -”

“Tails.” Sonic inserted, and several emotions flashed across Nezu’s face for the briefest of moments. 

“...Tails.” He amended. “Will Tails be able to join us or is he too worked up?” Giving several loud sniffles Tails wiped his nose and and gave a few nods. 

“I’m okay.” He said hoarsely. “As long as I can go with Sonic.” Nezu nodded and got off of his chair, Toshinori following his lead. 

The three of them got off of the couch and instantly Toshinori went behind them, sandwiching the trio between the two adults. It was sweet that they were taking protecting them so seriously, but also it was becoming progressively clearer and clearer that it would make finding the Emeralds or anything along those lines increasingly difficult. 

Eventually they turned off into a side room which was a large gym about the size of an aircraft hangar. There were weights, obstacle courses, a running track… It was impressive, sure, but more or less on par with the courses that Sonic had trained on over the years. Whatever had sent them here, and Sonic was still betting the Emeralds, it at least hadn’t left them helpless. Tails had a pair of overalls with a striped shirt and his normal sneakers. Knuckles had a tanktop, a necklace, a pair of jeans and green/red cowboy boots. And Sonic had a hooded tank, running shorts, running capris, and most importantly, had retained his specialized shoes. 

“Okay, if you can remember your quirks feel free to perform them - if not we’ll start narrowing it down.” Nezu said pulling out a clipboard. Sonic flashed a smirk at the other two. 

“So quirks are like… our special abilities right?” 

“If that’s what they called them where you were than yes.” Sonic’s form flickered. 

“There ya go.” 

“I- I’m sorry?” Principle Nezu raised an eyebrow. 

“I just did it for ya. Here let me just-” Running at a top speed - a very show offy speed, Sonic dashed down the hall, went back into the office, grabbed a pen from the desk, and came all the way back, extending it out for the Principle. “Here you go.” The wind had really picked up around him that time, leaving everyone’s hair waving and Nezu and Toshinori’s eyes wide open. 

“Did you just run all the way back to my office.” 

“Sure did - a light jog really.” Knuckles groaned behind Sonic. 

“Such incredible super speed.” Toshinori muttered, a hand lifted to his chin. “And what about you, young one?” The skeleton man looked at Tails. “What’s your quirk?” 

“Oh, uh.” Tails frowned for a minute, his namesakes swishing. “I can just show you-” Lifting himself off the ground with his helicoptering tails he gave a small wave. “Don’t ask me how they work like this - they just do.”

“Dear goodness!” Nezu applauded. “How unique!” Tails smiled at the attention and Sonic gave him a wink. “As for the last one - Knuckles if I recall correctly.” 

“Mine’s not as showy.” He muttered, fanning out his hand and showing his claws and knuckles. “Besides these things if you count them.” He trotted over the metal structure holding all of the weights and, grabbing it by it’s base, casually lifted it up. 

“Good lord.” Toshinori breathed out. “And how much can you carry?” Knuckles shrugged at the question. 

“Never really tested it out to be honest.” 

“Well,” Nezu took a deep breath. “Very good, thank you three for your cooperation. For now let us show you to your rooms.”

  
  


Later, Aizawa sat in front of a computer, furiously typing in the three kids quirks, trying all the different wording he could possibly conceive. The other teachers were there as well, along with the principle, faces grim. 

“Are they still not showing up?” Toshinori asked, anguish filling his voice as the situation began to look more and more for the worse. 

“I’m trying everything I can think of Aizawa retorted and Nemuri put a hand to her head, lips pressed tightly together. 

“I’m sorry but there’s only one reason I can think of for this.” She said, voicing what they’d all been thinking. “They have no memory of a regular home. They have some extraordinary quirks - even multiple quirks - and their names. They’re just descriptors. Sonic is just for speed. Tails and Knuckles are both self explanatory. They weren’t even given true names.” With an angry face Aizawa finished her thought.

“They must have been human quirk based experiments.”


End file.
